1. Field of the Invention
The invention relates to a motor rotor and its manufacturing method, and more particularly to a motor rotor having a rubber magnet with a pattern formed on the outer surface thereof for improving the flexibility of the rubber magnet of the motor rotor.
2. Description of the Related Art
A magnet is one of the essential components of a rotary machine, such as a motor. To reduce cost, cheap rubber magnets are used in conventional rotary machine structures.
The schematic structure of a conventional motor rotor adopting rubber magnets is illustrated in FIG. 1. As shown in FIG. 1, the band-shaped rubber magnet 100 with a predetermined dimension is bent into a ring in the manufacturing process of a motor adopting a rubber magnet 100. Then, the ring-shaped rubber magnet 100 is pressed into a magnetic yoke 102 to complete the assembly of a motor rotor 104.
However, in the process mentioned above, the rubber magnet 100 is not so flexible that the two end surfaces of the rubber magnet 100 cannot be jointed perfectly after the rubber magnet 100 is bent. This phenomenon becomes more significant as the thickness of the rubber magnet 100 increases. When the above phenomenon takes place, the motor suffers from the non-uniform distribution of the magnetic field or magnetic leakage, which results in the flutter of the motor. When this happens, not only the operation efficiency of the motor is reduced, but also high frequency noises are generated when the motor operates at high a speed.